Unsaturated esters and polymers thereof



um-rap STATES PATENT OFFICE UNSATURATED ESTERS AND POLYMERS THEREOF.-

Irving E. Muskat, Akron, and Franklin Strain,

Norton Center, Ohio, assignors to Pittsburgh Plate Glass Company,Pittsburgh, Pa., a corporation oi' Pennsylvania 1 No Drawing.Application June 8, 1942,

. Serial No. 446,288

8 Claims. (Cl. 260-78) This invention relatesto a new class of un- Manyof the esters have the general structure: saturated esters possessingvaluable properties O a as hereinafter described. They are the esters ofel: g l 1 1 (a) thehali ester of carbonic acid and an unsaturatedalcohol and (b) an hydroxy ester of a 5 in which RH is the orgfmicradical to which 1! simple polyhydroxy compound and a simple hyhydroxyps of e p e po v p y co droxy monocarboxylic acid. pound are attached.Rex is the orgamc radical By "ester-linkage" we mean a linking oxygen towhich i! earbexylic oups and r hydroxy t g -w d by i t t of a hydroxygroup groups of the hydroxy carboxylic acid are atand an 1 group Thus, acarbonate 1 tached and Rm is the radical derived from the Rr-OC()ORcontains two ester linkages. unsaturated alcohol- By simple polyhydroxycompound we mean The new COmDOImdS y be regarded s th any organiccompound having t or more neutralesters of the glycerol triesters ofhydroxy droxyl groups which are t separated by an aliphatic acids andthe unsaturated alcohol acid ester linkage. Thus, bis (ethylene glycol)carcarbonate esters- Thus, they are the esters of bonate is t lpo1yhydroxy compound, compounds such as castor oil (glycerol triricnoles t b imple polyhydrgxy compounds are t ate), glycerol trilactate orglycerol trisalicylate glycols such as ethylene glycol, propylene glycl, with the carbonic acid half esters such as allyl trlmethylene glycol,tetramethylene glycol, 1-3, acid carbonate methallyl acid b t dihydroxybutane, the dihydro'xy pentanes, 2o 7 The new esters may b preparedbyesierifying ricinoleyl alcohol, etc., the polyglycols such as a simplp y y y pm d w 9m? or 1mm di-, tri-, and tetraethylene glycol, di-,tri-, and moles of Simple hydroxy c to f m poly yd o y tetrapropyleneglycol, (11-, tri-, and tetrabutylene esters Such as ethylene glYCQl111$ a 137C015, t t aromatic polyhydroxy ethylene glycolmono lactate,ethylene glycol bis pounds such as resorcinol, pyrogallol, catechol, Y Yr ethylene g y l bis etc., or the higher polyhydroxy aliphatic Iricinoleate, etc., and the corresponding esters, of pounds such asglycerol, alpha methyl glycerol, p py ne glycol, trimethylene glycol,glycerol, erythrltol, pentaerythritol; dextrose, sucrose, etc. l ne gyco glycerol, e ch eydroxy y Simple hydroxy monocarboxylic a i we estersare prepared by heatingthe reactants on mean a compound which containsat least one an i ath to temperatures to. 15Q C. and in hydroxy group,and one carboxyl group w do the presence of an esterification catalystsuch as not, however, intend to include compounds which p e sulphonicacid or, toluene lp ic acid. have an ester linkage within the moleculesuch intelmediate s e thus prepared re reas lactyl lactic a id actedwith the chloroforrnates of unsaturated CH: 0 CH 35 alcoholsto preparethe new esters. The chloro- E 5 g 5 a formate is added to the hydroxycompound while H-O- H-oH maintaining the temperature between 0 and 20Suitable simple hydroxy monocarboxylic acids C. The reaction isconducted in the presence are glycollc, lactic, hydracrylic,a-hydroxybutyric, of an alkaline reagent such as pyridineorotherp-hvdroxybutyric, salicylic, phloretic, melilotic, 4,0 cyclic, tertiaryamine or theoxide, hydroxide, or coumaric, vanillic, leucinic,-va1erolactinic, acecarbonate of an alkali or alkaline earth. metal.tonic, ricinolelc, glycerlc, gallic, saccharinic, When an hydroxide, orcarbonate of an alkaline divaric, protocatechuic, and the variousresorcylic earth metal such as calcium carbonate is used acids. as thealkaline agent, higher reaction tempera- The new compounds arepreferably the este 4s tures are desirableto promote a practicable rateoi unsaturated alcohols having up to five carbon of reaction. When verystrong alkalinereagents atoms and an unsaturated. linkage in an alisuchas sodium or potassium hydroxide are used, phatic chain such .as allyl,methallyl, chloroallyl, it is frequently desirable to reverse the orderof crotyl, tigiyl, chlorocrotyl, ethylallyl, propargyl, combining thereagentsand add the alkaline and angelyl alcohols, methyl vinylcarblnol, ethyl so agent a mixture o t hydrexy c mp u and vinylcarbinol, divinyl carbinol. dimethyl vinyl the chloroformate inorder toavoldf h olysis carbinol, etc. Esters of alcoholsv having six to of theester; The esterification reactionsmay be ten carbon atoms are alsouseful suchas geranyl, conducted in the presence of an inert solventoinnan' yl, phenylpropargyl, and p-propyl-allyl such as benzene,toluene, diethyl other, carbon alcohols, and ethyl dlvinyl carbinol. o5m rlderetm um her, e I9? s PW- pose of maintaining a liquid phasereaction or to dilute the reactive mixture.

The same compounds may be synthesized by treating said intermediateester such as dlethylene glycol bis lactate, glycerol bis lactate, 6

ture of unsaturated alcohol and an alkaline agent such as pyridine,NaOH, CaCOa, etc., while maintaining the temperature between 0 C. and C.by means of an ice bath and a stirrer to avoid local overheating. It isusually desirable to 0perate in a liquid medium. Accordingly, it is fre-20 quently necessary to add a suitable solvent such as benzene, diethylether, acetone, petroleum etther, toluene, or carbon tetrachloride.

The new unsaturated carbonates are generally non-resinous compoundshaving distinct boiling and melting points and are often capable ofseparation in substantially pure state. Frequently, the impurities areside reaction products which are colorless and transparent esters havingcharacteristics similar to the esters herein contemplated. In such casesremoval of said impurities may be unnecessary where they do not produceany detrimental effect in the use to which the ester is put. The newcompounds are usually liquid at room temperature buts-59mg. however, 3

are solids. 7 usually miscible with solvents such as benzene, toluene,chloroform, diethyl ether, carbon tetrachloride, and petroleum ether.The monomeric esters are valuable as plasticizers for various resinmaterials such as styrene, cellulose, vinyl, urea, protein, phenolic, oracrylic resins. Other uses such as solvents, insecticides, and liquidcoating compositions are noteworthy.

These esters may be polymerized in the presence of heat, light, orcatalysts such as oxygen, ozones, or organic peroxides such as lauroyl,benzoyl, and acetone peroxides, to yield solid The new unsaturatedcompohndsare or liquid compositions-of widely diifering physicalproperties. The polymerized products vary in properties depending uponthe structure of the ester and upon the degree of polymerization.

Compounds having a single unsaturated group are polymerizable intoreadily thermoplastic materials capable of uses to which the commonvinyl polymers such as vinyl acetate, etc., are usually put. A preferredgroup of new compounds are those which contain two or more unsaturatedgroups and especially those which are completely esterified (i. e.)containing no unreacted acid and hydroxyl groups. These polyunsaturatedesters are capable of polymerization to a fusible intermediate stage andfinally to a substantially .infusible and insoluble polymer. Theultimate polymers of these new compounds are generally unaffected byacids, alkalies, water, and organic solvents. The polymers thus obtainedare usually colorless and transparent although in some cases they'may beslightly yellow when polymerized completely. Many of these polymers aretougher and more. resistant to shattering than are the unsaturatedalcohol diesters of simple polybasic acids.

Upon the initial polymerization of the polyunsaturated esters in liquidmonomeric state or aseaosa in a solution of the monomer in suitablesolvents, an increase in the viscosity of the liquids is noticeable dueto the formation of a relatively low molecular weight polymer which issoluble in the monomer, and in solvents such as acetone, benzene,xylene, dioxane, toluene, or carbon tetrachloride. Upon furtherpolymerization, the liquid sets up to form a soft. gel containing asubstantial portion of a polymer which is insoluble in the monomer andorganic solvents and containing as well, a substantial portion of asoluble material which may be monomer and/or soluble fusible polymer.These gels are soft and bend readily. However, they are fragile andcrumble or tear under low stresses. They may be further polymerized inthe presence of catalysts to the final infusible insoluble state inwhich substantially all of the polymer is substantially infusible andsubstantially insoluble in organitr solvents, acids, and alkalies.

The monomers of the polyunsaturated esters may becast polymerizeddirectly to the substantially insoluble, infusible state. This procedureis subject to certain inherent difliculties due to the strains which areestablished during polymerization of the gel and which frequently re:sult in fractures as the final hard form is attained. It has beendiscovered that these dimculties may be avoided by releasing the strainsestablished in the gel before the fracturing can occur. This may be doneby permitting the strains to be relieved before the polymerization iscomplete, either periodically or by conducting the polymerization underconditions which permit gradual release of these strains. For example,the polymerization may be conducted in a simple mold until a soft firmgel has formed. At this point the polymer may be freed from the mold towhich it adheres strongly. polymer contracts substantially, therebyrelieving the polymerization strains. The gel may thereafter be shaped,if desired, and polymerized to the final infusible state. Smooth,optically perfect sheets may be made by this method. Preferably, theinitial polymerization is conducted at a temperature sufficiently low toprevent the complete decomposition of the peroxide catalyst. Thetemperature is dependent upon the catalyst used. For benzoyl peroxide,temperatures of to C. are suitable, while for acetone peroxide,temperatures of 140-150 C. may be used. In accordance with onemodification, the gel, after it is freed from the mold, may be coated onboth sides with monomer or the syrupy polymer. The coated article isthen polymerized between smooth heated plates to the final insolublestate.

Cast polymers may also be prepared by a single step polymerizationdirectly to the insoluble infusible state. The monomer may be mixed with0 up to five percent of benzoyl or other organic peroxide and heated at50 to 60 C. until it becomes partly polymerized and thickened to anincreased viscosity of to 1000 percent of the monomer viscosity. Thethickened monomer may then be polymerized between glass, metal, orsimilar plates which are separated by compressible gaskets or retainersof Koroseal, butadiene polymers, polyvinyl alcohol, Thiokol, rubber, orsimilar materials arranged about the edge of such plates. The thickenedmonomer may be poured on one glass plate within the confines of theflexible retainer, laid about two inches from the edge of the plate. Thesecond glass plate may then be carefully laid on top, taking care toavoid the trapping of air bubbles under the top plate.

When released the aseaose When the top plate is in position, both platesmay be held together by means of suitable clamps which are capable ofapplying pressure upon the plates directly over the flexible retainer.The entire assembly is then placed in an oven and heated at 70 to 100 C.where the polymerization is continued. During the polymerization theresin shrinks an tends to draw away from the glass surface. To preventfractures pressure is maintained upon the plates to depress the flexiblecontainer and permit the plates to remain in contact with thepolymerizing resin. This pressure may be maintained by periodicallytightening the clamps or by use of spring clamps which maintains auniform pressure throughout the polymerization process.

By an alternative procedure, for east polymerizing sheets, the molds maybe assembled before the thickened monomer is poured. Thus, the flexiblecompressible retainer may be inserted between the plates and held inplace by suitable clamps located around the edge of the plates. Thisretainer or gasket is placed adjacent the edge of the plates and asuitable opening provided between the ends of the flexible retainer,preferably at one corner of the mold. The assembled mold is then placedin a vertical position with the open corner uppermost. The thickenedmonomer which may contain up to four percent residual peroxide is thenpoured in slowly until the entire mold is filled. After standing untilall of the entrapped air has separated, the mold is heated uniformlybetween 50 and 100 C., to continue the poly,- merization. Pressure ismaintained upon the plates to ensure the contact of glass and resinduring polymerizable by suitable means, such as by tightening the clampsperiodically or by maintaining a uniform pressure upon the platesthroughout by means of spring clamps. When the resin has been completelypolymerized it is separated from the glass plates and a hard,transparent, colorless, and durable resin sheet is obtained.

Other methods have been developed for polymerization of the compoundsherein contemplated while avoiding formation of cracks and fractures. Byone of these methods the polymerization may be suspended while themonomerpolymer mixture is in the liquid state and before the polymer isconverted to a gel by cooling, by removal from exposure to ultravioletlight, by adding inhibiting materials such as-pyrogallol, hydroquinone,aniline, phenylene diamine, or sulphur, or by destruction of thepolymerization catalyst. The fusible polymer may be separated from allor part of the monomer by any of several methods. It may be precipitatedby the addition of nonsolvents for the fusible polymer such as water,ethyl alcohol, methyl alcohol, or glycol. Alternatively, it may also beseparated from the monomer by distillation in the presence of aninhibitor for polymerization and preferably at reduced pressures. Thefusible polymer is thus obtained in stable solid form and as such may beused as a molding powder or may be redissolved in suitable solvent foruse in liquid form. It is soluble in organic solvents which are normallycapable of dissolving methyl methacrylate polymer or similar vinyl typepolymer. Preferably, the polymers of the new esters are produced byheating the monomer or a solution thereof in the presence of substantialquantities, for example, 2 to 5 percent of benzoyl peroxide until theviscosity of the solution has increased about 100 to 500 percent. Thismay require several hours while heating at 65 to 85 C. in' the presenceof benzoyl peroxide. The resulting viscous solution is poured into anequal volume of water, methyl or ethyl alcohols, glycol or othernonsolvent for the fusible polymer. A I polymer, usually in the form ofa powder or a gummy precipitate is thus formed which may be decanted orfiltered and then dried. This permits substantially complete separationof a soluble fusible polymer from unpolymerized monomer.

1 Often, however, a complete separation of monomer and polymer is notdesirable since hazy products may be secured upon furtherpolymerization. Accordingly, it is often desirable to producecompositions comprising the fusible polymer and the monomer. This may beeffected by partial distillation or extraction of monomer from thepolymer or by reblending a portion of the fusible polymer with the sameor a different polymerizable monomer. In general, the composition shouldcontain polymer and from about 5 percent to 50 or 60 percent monomer.Preferably, the production of these materials is conducted by treatmentof a solution of the monomer in a solvent for monomer and polymer, suchas benzene, xylene, toluene, carbon tetrachloride, acetone, or othersolvent which normally dissolves vinyl polymers.

Other polymerization methods may involve the interruption of thepolymerization while the polymer is a gel. For example, a soft solid gelcontaining a substantial portion of fusible polymer may be digested witha quantity of solvent for the fusible polymer to extract the fusible gelfrom the infusible. The solution may then be treated as above describedto separate the fusible polymer from the solvent. These poly-mers may beused as molding or coating compositions. Due to their solubility, theyare particularly desirable for use in paint compositions.

Other fusible polymers may be prepared by carrying the initialpolymerization to the point where the polymer. is in the form of a gelwhich generally contains at least 20 percent and preferably about 45 topercent by weight of substantially insoluble polymer, but at which pointthe gel is still fusible. This solid resin composition may bedisintegrated to a pulverulent form and used as a molding powder.Alternatively, a desirable polymer may be prepared by emulsifying themonomer or a syrupy polymer in an aqueous medium with or without asuitable emulsification agent such as polyvinyl alcohol, polyallylalcohol,

'etc., and then polymerizing to the point where the gel precipitates.This polymer may be separated and used as molding powder.

The solid forms of the fusible polymers may be used as moldingcompositions to form desirable molded products which may be subsequentlypolymerized to an infusible state. Preferably, the molding is conductedin a manner such that the polymer fuses or blends together to form asubstantially homogeneous product before the composition is polymerizedto the substantially infusible state. This may be effected by conductingpolymerization at an elevated temperature and/or pressure in thepresence of benzoyl peroxide,

.generally in a. heated mold. The polymers may be mixed with fillerssuch as alpha, cellulose, wood pulp, and other fibrous substances,mineral fillers or pigments such as zinc oxide, calcium carbonate, leadchromate, magnesium carbonate, calcium silicate, etc.; plasticizers suchas the saturated alcohol esters of phthalic acid, camphor, the saturatedalcohol esters of maleic,

attractively finished coatings.

fumaric, succinic, and adipic acids or dior'triethylene glycol bis(butyl carbonate). The poly- -chloroform, acetone, dioxane, carbontetrachloride, phenyl Cellosolve, dichlorethyl ether, dibutyl phthalate,or mixtures thereof, is useful as a liquid coating composition. Objectsof paper, metal, cloth, wood, leather, or synthetic resins may be coatedwith the solution of polymer in solvent and subsequently polymerized toyield Similarly, porous objects of felt, cloth, leather, paper, etc.,either in single layers or laminated, may be impregnated with thedissolved fusible polymer and subjected to the polymerization to thefinal infusible insoluble state. Other molding powders may be preparedfrom the new esters without first converting them to the intermediatepolymer. The monomer may be mixed directly with a suitable filler suchas magnesium carbonate, cellulose pulp, as-

bestos, etc., ,in a ball mill or other mixing device. By proper.selection of proportions, a dry pulverulent powder can be obtained whichis capable of polymerization under the influence of heat and pressure toa glossy solid polymer of high tensile strength. The use of too muchfiller will cause a non-glossy finish and the use of too a much monomerwill make the powder moist and diflicult to handle. Sometimes it may bedesirable to precure the molding powder by subjecting it to a moderatetemperature of 50 to 70 C. for a limited period of time, for example,one to three hours, and this precuring operation is a partialpolymerization and permits a dry mold ing powder where the sameproportions of monomer might result in a moist moldingcomposition.

The following examples are illustrative:

Example I Glycerol (95 grams) and three molar equivalents of lactic acid(280 grams) were heated on a water bath for 18 hours in the presence of1.1' grams p-toluenesulphonic acid to catalyze the reaction. A mixtureof the monolactate and dilactate of glycerol was formed. The esters weremixed with 1000 cc. benzene and 275 grams of pyridine, and cooled to +2C. 375 grams of allyl chloroformate were added slowly to prevent theheating of the reaction mixture to a point above 15 C. The benzenesolution of the carbonate esters was washed with sodium carbonatesolution, with hydrochloric acid, and with water until neutral. Afterdrying over calcium chloride, the solution was heated at 75 to 80 C. toevaporate the benzene, a viscous liquid ester being secured.

he ester mixture was heated at 75 C. in the presence of 3 percentbenzoyl peroxide. A hard solid polymer was obtained.

Example II One kilogram of castor oil was mixed with 2000 cc. benzol and250 grams pyridine. It was cooled to +2 C. on an ice bath. Withcontinuous stirring to dissipate the heat of reaction,

360 grams of allyl chloroformate was slowly added at the rate 015 gramsper minute for 15 minutes.

The rate of addition was then increased to 10 grams for the next 15minutes. The balance was then added at 18 to 25 grams per minute. Whenthe addition was completed the mixture was maintained at the reactiontemperature of +2 to +5 C. for an hour with uninterrupted 5 percent ofbenzoyl peroxide.

Example III Sixty-five grams of ethylene glycol, 225' grams of salicylicacid, 15 grams of anhydrous aluminum sulfate, and 1000 cc. of benzenewere refluxed for three hours.- The vapors were condensed and thebenzene separated from the water and returned to the reaction by acontinuous apparatus. After the evolution of water ceased, the benzenesolution was washed with two 50 cc. portions of saturated sodiumsulphate solution and dried over anhydrous sodium sulphate. The solutionofethylene disalicylate was cooled to +2 C. and mixed with 165 grams ofpyridine. 250 grams of methallyl chloroformate were added at a ratewhich enabled the dissipation of heat of reaction and the maintenance ofthe reaction temperature below 10 C. When the reaction was complete theexcess pyridine was neutralized with HCl and the benzene solution washedwith water. The benzene and other volatile impurities were evaporated byheating at 50-60 mm. total pressure. The ester formed is a liquidbelieved to have the following structure:

Example I V Ethylene glycol grams) was esterifled with two gram molarequivalents of lactic acid (250 grams) in the presence of 2 grams ofanhydrous aluminum sulfate and 1000 cc. of benzene. The esterificationwas performed by refluxing for two hours with a continuous separatorycondenser. for removing the water of reaction. When the reaction wassubstantially complete the benzene solution of glycol dilactate wascooled to 0 C. and mixed with 350 grams of allyl chloroformate. A 200cc. quantity of 50 percent sodium hydroxide was added dropwise at a rateof two to three cubic centimeters per minute. After 50cc. were added therate was increased to about 4 to 5 cc. At the end of the addition thisrate had been increased 6 to 8 cc. per minute. This slow butprogressively increasing rate of. addition enabled the maintenance oftemperature between +2 and +8 C. The ester solution was washed withdilute hydrochloric acid, with water until neutral, and then dried withcalcium chloride. The ester was purified by evaporating the benzene andother volatile impurities. The ester was a colorless liquid having thefollowing structural formula:

Example V Propylene-1,2-diglycolate was prepared in benzene solution. byesterirlcation of 160 grams of glycolic acid and 110 grams of1,2-propylene glycol. The reaction was conducted in the presence of 1200cc. of benzene and 1.5 grams of anhydrous aluminum sulfate by heatingthe mixture at the reflux temperature. The condensate was separated intothe two liquid phases and the benzene returned to the esteriflcationvessel. As soon as the reaction ceased to evolve water the mixture wascooled to C. and mixed with 200 grams of pyridine. While maintaining thetemperature between 0 0.. and 12 C. by cooling, stirring, and regulatingthe rate of addition of reactants, an excess of crotyl chloroformate wasadded. The benzene solution was thereafter washed with dilutehydrochloric acid and with water until neutral to phenolphthalein. Afterdrying over anhydrous Nazsoi the benzene was vaporized and a clear,colorless liquid ester was obtained. The ester was believed to have thefollowing structure:

Example VI Dlethylene glycol (108 grams) and a-hydroxy butyric acid,(208 grams) were mixed with 1500 cc. benzene and 2.5 grams of anhydrousaluminum sulfate. The mixture was heated four hours at the refluxtemperature. The vapors were condensed and intermittently the benzenewas separated irom the water and returned to the reaction'vessel. At theend of four hours no more water was being evolved. The benzene solutionwas washed with 100 cc. of water and dried with anhydrous NazSOa Thediethylene glycol bis (a-hydroxy butyrate) was mixed with 185 gramspyridine and treated with 250 grams of allyl chlorotormate as describedin Example IV. During the reaction the temperature was maintainedbetween +4 and +16 C. The benzene solution was washed with dilute acidto remove the pyridine and pyridine hydrochloride and with water. Thesolution was dried over anhydrous sodium sulfate. The diethylene glycolbis -oxy(earballyloxy)butyrate was freed or benzene by heating at 8-10mm. total pressure. The ester was a colorless liquid having the probableformula:

tn. 0 can 0 Example VII A fifty gram sample of the monomeric esterdescribed in Example IV was dissolved in 300 cc. of benzene. Two gramsof benzoyl peroxide were added and the solution heated for three hoursat 65 C. The solution increased in viscosity to about 300 percent. ofthe monomeric viscosity. The viscous liquid was then poured into 500 cc.of methyl alcohol causing a separation of a solid precipitate- The solidwasseparated by decantation and washed with methyl alcohol. After dryinga granular resinous solid was obtained. A

ten gram sample was heated to 135 C. in a. mold under 1500 lbs. persquare inch pressure for about one hour. A hard, tough polymer wassecured.

This application is a continuation-in-part of Serial No. 361,280, filedOctober 15, 1940, and Serial No. 403,703, filed July 23, 1941, by IrvingE. Muskat and Franklin Strain.

Although the invention is described with re spect to certain specificexamples, it is not intended that the details described shall belimitations upon the scope of the invention except as expressly includedin the appended claims.

We claim:

1. A neutral ester of one molecular equivalent of castor oil and threemolecular equivalents of of allyl acid carbonate.

v2. A neutral ester of one molecular equivalent of glycerol trilactateand three molecular equivalents of methallyl acid carbonate.

3. A neutral ester of one molecular equivalent of glycerol trisalicylateand three molecular equivalents of the carbonic acid half ester of allylalcohol.-

4. A polymer of the compound defined in claim 1.

5. A polymer of the compound defined in claim 2.

6. A polymer of the compound defined in claim 3.

'7. As a new compound an ester having the molecular structure:

- atoms and having an unsaturated carbon to carbon bond between thesecond and third carbon atoms from the oxygen atom adjacent to saidalkenyl radical, a: is a small whole number and y is a small wholenumber greater than one.

8. As a new compound an ester having the molecular structure:

wherein Rn is a divalent saturated aliphatic radical, Rm is anhydrocarbon radical having a valence equal to (2+1), Rn is an alkenylradical having at least three carbon atoms and having an unsaturatedcarbon to carbon bond between the second and third carbon atoms from theoxygen atom adjacent to said alkenyl radical, and a: and n are smallwhole numbers.

IRVING E. MUSKA'I'. FRANKLIN STRAIN.

